5 Things You Need to Know About Making Biodiesel at Home

Biodiesel, a petroleum-based diesel alternative produced by transesterification, works as efficiently as the commercially sold diesel and hardly requires any changes in the engine. For those who don’t know, biodiesel can be produced using any oil derived from plants such as soybean oil, cottonseed oil, canola oil, etc. or from animal fats, like beef tallow and chicken tallow.

Over the past five years, due to the spike in fuel prices, people have started moving towards energy independence and have started small private biodiesel production units. According to reports, biodiesel made from useless tires could solve fuel security problems. Tires are a big problem as they create a lot of waste. We can turn this waste into useful oil and help not only the environment but also the economy.

If you are new to biodiesel production, some of the crucial things to know are:

1. Safety

This should not come as a surprise, safety rules are necessary to avoid the contamination of soil and water resources, fires, and personal poisoning.

Vegetable oil to biodiesel conversion requires methanol and lye. Both these chemicals are extremely dangerous since they are not only inflammable but can also cause neurological damage in case of excessive exposure.

A number of biodiesel related accidents and fires have been reported over the last few years. The incidents were a result of pure neglect. Some of the safety measures you should never forget to take are:

  • Don’t process inside your house.
  • Don’t keep any oily rags in the vicinity, they are the main source of spontaneous combustion leading to huge fires.
  • Don’t use paint stirrers or drills to mix up the biodiesel. It can cause a fire.
  • Don’t use blenders to make test batches, the ingredients can react with rubber seals.

All hazardous and dangerous products should be kept in an approved metal fire cabinet when not in use.

2. Environmental Regulations and Feedstock Collection

Currently, non-commercial and small-scale biodiesel production areas are not subjected to regulations by the Department of Environmental Protection (PADEP). However, if complaints or problems arise due to your biodiesel product, your plant might be subjected to discretionary enforcement. Moreover, you’ll need approval if you wish to increase the size of the production unit.

The disposal of by-products, on the other hand, requires the approval of the PADEP and should be done based on the latest guidelines. These guidelines can be obtained from your local Department of Environmental Protection.

Apart from following the rules and regulations, the availability of feedstock is crucial for the process.

One gallon of biodiesel requires at least one gallon of feedstock oil. To reduce production costs and to prevent food for fuel conflict, using inedible oils as a major source for biodiesel production is advised.

Usually, feedstock and feedstock oil are difficult to obtain, hence pre-planning is the key to produce the required amount of biodiesel on a regular basis. The collection and transportation of feedstock including used cooking oils are regulated by PADEP.

3. Time Commitment and Cost Requirements

New users usually underestimate the time requirements for proper and regular biodiesel production. While planning your biodiesel plant, make sure you allocate enough time to maintaining the equipment since improper maintenance lead to accidents. Feedstock collection and fuel processing also require a lot of time.

Other time-consuming tasks include handling and securing chemicals, air drying and water washing the fuel, testing the duel quality, and disposing of by-products.

Even though the cost requirements per gallon of biodiesel fuel process are much lower than the commercially sold diesel, there are a few things you need to take into consideration beforehand.

A detailed analysis of input costs versus the resultant value of fuel produced needs to be performed. The analysis should also include labor costs.

Investment in equipment and facility, feedstock transport and acquisition, chemicals, energy used and by-product disposal costs need to be accounted for as well.

4. Handling and Disposing By-products

During the production process, a considerable amount of crude glycerol is produced. Other processors that use water for biodiesel purification produced two gallons of waste for every gallon of biodiesel.

Handling this amount of waste can be taxing. It needs to be compliant with the PADEP rules and regulations. This not only requires more time but capital as well.

The crude glycerol by-product has 25 percent methanol as well as some hazardous waste. Converting it into marketable glycerin is not feasible on a small-scale since the evaporation of methanol cannot be contained.

The land application of methanol and glycerol are prohibited by PADEP. The disposal options from crude glycerol including methanol are:

  • Disposing of in a landfill.
  • Anaerobic digestion.
  • Industrial combustion.

You have to get special permission from PADEP for all the above processes.

5. Fuel Quality and Storage

Commercial testing of the fuel quality can rip you off since one batch can cost anything between $1000 and $1500. However, simpler fuel testing techniques like sediment testing, methanol testing, water content, viscosity, and cloud point testing can help you find a rough estimate of how good or bad the fuel is. These tests can also help you in finding what needs to be improved during the production process.

To store the fuel, use proper, biodiesel approved and rubber free containers. Using in-line filters while pumping the fuel in storage containers is the best practice. Usually, biodiesel produces use of 10-micron water-blocking filter or a 1-micron filter.

Petroleum approved containers also work well for storing biodiesel. Once in containers, the fuel should be kept in a dry, clean, and dark environment.

If you plan on storing the fuel for a longer time, using algaecide or fungicide additive is recommended since biodiesel is an organic liquid. Also, during cold seasons, the fuel gels, hence, blending in petroleum or anti-gelling additive is pretty important.

For best engine performance, you must use it within six months. If you can, limit the storage time to 3 months in warm and humid weather since the fuel can develop algae or fungus.

Pyrolysis of Scrap Tires

scrap-tires-pyrolysisPyrolysis of scrap tires offers an environmentally and economically attractive method for transforming waste tires into useful products, heat and electrical energy. Pyrolysis refers to the thermal decomposition of scrap tires either in the absence or lack of oxygen. The principal feedstocks for pyrolysis are pre-treated car, bus or truck tire chips. Scrap tires are an excellent fuel because of their high calorific value which is comparable to that of coal and crude oil. The heating value of an average size passenger tire is between 30 – 34MJ/kg.

Pyrolysis is the most recommended alternative for the thermochemical treatment of waste tires and extensively used for conversion of carbonaceous materials in Europe and the Asia-Pacific. Pyrolysis is a two-phase treatment which uses thermal decomposition to heat the rubber in the absence of oxygen to break it into its constituent parts, e.g., pyrolysis oil (or bio oil), synthetic gas and char. Cracking and post-cracking take place progressively as the material is heated to 450-500°C and above.

Process Description

The pyrolysis method for scrap tires recycling involves heating whole or halved or shredded tires in a reactor containing an oxygen free atmosphere and a heat source. In the reactor, the rubber is softened after which the rubber polymers disintegrate into smaller molecules which eventually vaporize and exit from the reactor. These vapors can be burned directly to produce power or condensed into an oily type liquid, called pyrolysis oil or bio oil. Some molecules are too small to condense and remain as a gas which can be burned as fuel. The minerals that were part of the tire, about 40% by weight, are removed as a solid. When performed well a tire pyrolysis process is a very clean operation and has nearly no emissions or waste.

The heating rate of tire is an important parameter affecting the reaction time, product yield, product quality and energy requirement of the waste tire pyrolysis process. If the temperature is maintained at around 450oC the main product is liquid which could be a mixture of hydrocarbon depending on the initial composition of waste material. At temperature above 700oC, synthetic gas (also known as syngas), a mixture of hydrogen and carbon monoxide, becomes the primary product due to further cracking of the liquids.

Schematic for Pyrolysis of Scrap Tires

Schematic for Pyrolysis of Scrap Tires

The nature of the feedstock and process conditions defines the properties of the gas, liquid and solid products. For example, whole tires contain fibers and steel while shredded tires have most of the steel and sometimes most of the fiber removed. Processes can be either batch or continuous. The energy required for thermal decomposition of the scrap tires can be in the form of directly-fired fuel, electrical induction and or by microwaves (like a microwave oven). A catalyst may also be required to accelerate the pyrolysis process.

Useful Products

The high acceptance of pyrolysis for the treatment of scrap tires is due to the fact that the derived oils and syngas can be used as biofuels or as feedstock for refining crude oil or chemical products. The pyrolysis oil (or bio oil) has higher calorific value, low ash, low residual carbon and low sulphur content.

The use of pyrolysis oil in cement kilns, paper mills, power plants, industrial furnaces, foundries and other industries is one of the best uses of scrap tires.  Pyrolysis of scrap tyres produces oil that can be used as liquid fuels for industrial furnaces, foundries and boilers in power plants due to their higher calorific value, low ash, residual carbon and sulphur content.

The solid residue, called char, contains carbon black, and inorganic matter. It contains carbon black and the mineral matter initially present in the tire. This solid char may be used as reinforcement in the rubber industry, as activated carbon or as smokeless fuel.